Using inbred mice as our model system, we wish to determine the effects of dietary zinc deficiency on the immune response at different stages of development. In addition, we wish to ascertain whether or not these effects are temporary or permanent. Thus far, our studies show that the thymuses of weanling and young adult mice are completely destroyed after three to four weeks on a diet containing less than 1 ppm of zinc. T-Cell helper function is reduced in such mice, but B-cells can continue to proliferate reasonably well once they are stimulated. Since T-cells are critical to the defense of the host against disease, studies are planned to further delineate the effects of zinc deficiency on the immune response. The specific questions that we propose to study are as follows: What effect does zinc deficiency have on the cell-mediated and humoral arms of the immune response? What effect does zinc dificiency have on immunity in the neonatal and weanling animal and does it result in permanent damage? What effect does zinc deficiency during pregnancy have on the immune capacity of the offspring? To what degree can the effects of zinc on the immune system be reversed by the addition of adequate amounts of zinc to the diet? Although it is an accepted fact that individuals suffering from malnutrition are more susceptible to disease, very few studies have been done to determine why the immune system is impaired. We feel that the studies which we propose will increase our understanding of the relationship between malnutrition and disease.